Original paper
Anatomy of the glochidia of the freshwater pearl mussel, Margaritifera margaritifera (L.)
Pekkarinen, Marketta; Valovirta, Llmari
Archiv für Hydrobiologie Volume 137 Number 3 (1996), p. 411 - 423
45 references
published: Sep 5, 1996
DOI: 10.1127/archiv-hydrobiol/137/1996/411
ArtNo. ESP141013703006, Price: 29.00 €
Abstract
The glochidia dissected from the marsupial gills of Margaritifera margaritifera (L.) collected from the River Ähtävänjoki in western Finland were studied using light microscopy, scanning and transmission electron microscopy (SEM and TEM). The glochidial shells had a mean length of 69 μm and a mean height of 77 μm. The periostracum-covered shell valves were non-pitted and very thin, kept together by a small adductor muscle. The shells had no hooks or spines; the attachment to a host fish may be tightened by fluid-filled periostracal flanges, which turn inside from the shell edges. The inner periostracum of the flange originated from a groove near the margin of the larval mantle. No larval thread was discovered. There were only two pairs of sensory hair tufts located ventrally, and a few cilia occurred at the centre of the glochidium. The foot rudiment was equipped with long cilia, and the lateral pits harboured shorter cilia. The mantle comprised two layers and an intrapallial cavity between them. The mantle cells had large granules, which showed both basophilia and acidophilia, and the inner mantle cells had long microvilli projecting towards the mantle cavity. The extensive mantle may be multifunctional serving in absorption and digestion of nutrients, excretion, respiration and regulation of salt and water. The thin shell may also allow gaseous exchange but also may offer a route for entry of harmful substances, such as protons from acidified water.
Keywords
Ähtävänjoki • Finland • freshwater pearl mussel